Conventional recording heads for linear tape drives have small transducers incorporated into a large head assembly to span the full width of the tape. For recording heads fabricated using thin film wafer technology, this requires that the head either be fabricated individually on a wafer which is at least as wide as the recording tape and lapped individually to the proper shape, or be fabricated as a small part and assembled with larger pieces. In the second case, either the small parts or the full assembly is lapped to the proper shape.
Prior art FIG. 1 illustrates a wafer 100 on which a plurality of heads 102 may be manufactured. It should be noted that the wafer 100 is set forth for illustrative purposes only and the exact configuration of the wafer 100 may vary per the desires of the user. As shown, the wafer 100 includes two columns of multiple rows of heads 102. During the fabrication of the wafer 100, an array of heads 102 including transducers and auxiliary circuits are fabricated on a common substrate in a deposition of metallic and non-metallic layers. The auxiliary circuits are sometimes referred to as electrical lapping guides (ELGs). Patterning of the array of transducers and ELGs is accomplished using photolithography in combination with etching and lift-off processes. The finished array or wafer is then optically and electrically inspected and subsequently cut into smaller arrays of heads 102. Next, individual heads 102 are machined, at a surface 106 which will eventually face the recording medium, to obtain a desired read transducer height (sometimes referred to as the stripe height (SH) and a desired inductive transducer height (sometimes referred to as the throat height (TH).
During the manufacturing process, the surface 106 of each head 102 is lapped before being removed from the wafer 100. Such lapping reduces the height of the transducers. The primary function of the ELG(s) is to control the machining process such that the desired transducer height is achieved. After a particular row of transducers is machined to the desired transducer height as controlled by the ELG(s), the heads 102 are cut from the wafer 100. During this process, the ELG(s) can be destroyed if desired.
Typically, each ELG includes one or two resistors which are fabricated in the deposition of layers along with the transducers of the heads 102. A very simple ELG design has one resistor which is aligned with a transducer such that the machining process reduces the height of both the transducer and the resistor at the same time. The resistance of the machined resistor is monitored to determine when the desired height of the transducer has been achieved so that the machining process can be halted at this point.
In order to carry out the foregoing process utilizing the ELGs, an electrical connection must be established between the ELGs and a testing device. This is conventionally accomplished by way of a plurality of contacts 110 formed on each of the heads 102.
Prior art FIG. 2A is top plan view of a lapping cable 200 which is traditionally employed to connect a testing device to the contacts 110 formed on each of the heads 102. It should be noted that the lapping cable 200 is set forth for illustrative purposes only and the exact configuration of the lapping cable 200 may vary per the desires of the user. As shown, the lapping cable 200 is formed from a thin resilient material having a rectangular configuration. Such lapping cable 200 includes a plurality of wires 202 embedded therein which terminate at exposed planar contact pads 204 that are adapted to remain in electrical communication with the contacts 110 formed on each of the heads 102 during the lapping process. Prior art FIG. 2B is a cross-sectional view of the lapping cable 200 taken along line 2B-2B of FIG. 2A showing the planarity of the contact pads 204.
While the lapping cable 200 of FIG. 2A works well with the prior art wafers 100 of FIG. 1, difficulty arises when used with wafers having rows of closures formed thereon.
Prior art FIG. 3 illustrates a wafer 300 including a plurality of strips of closures 302 attached thereto. Such closures 302 define a plurality of slots 304 in which the aforementioned contacts 306 associated with the ELGs reside. Such closures 302 have recently become a common part of wafer processing in view of the benefits they afford in resultant heads. More information on the manufacture and use of closures 302 and the related benefits may be found with reference to U.S. Pat. Nos. 5,883,770 and 5,905,613 which are incorporated herein by reference in their entirety.
While such closures 302 of FIG. 3 afford various benefits, they cause complications in the lapping process. In particular, it is impossible for the contact pads 204 of the lapping cable 200 of FIGS. 2A & 2B to make contact with the contacts 306 positioned between the closures 302 of the wafer 300 of FIG. 3.
There is thus a need for an apparatus and method for affording electrical communication between a lapping cable and the contacts of a wafer during the lapping process associated with thin-film head manufacture involving closures.